-*- Autoconf -*-
# C M4 Macros for Bison.
-# Copyright (C) 2002, 2004, 2005, 2006, 2007 Free Software Foundation, Inc.
+
+# Copyright (C) 2002, 2004-2013 Free Software Foundation, Inc.
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
+m4_include(b4_pkgdatadir/[c-like.m4])
+
+# b4_tocpp(STRING)
+# ----------------
+# Convert STRING into a valid C macro name.
+m4_define([b4_tocpp],
+[m4_toupper(m4_bpatsubst(m4_quote($1), [[^a-zA-Z0-9]+], [_]))])
+
+
+# b4_cpp_guard(FILE)
+# ------------------
+# A valid C macro name to use as a CPP header guard for FILE.
+m4_define([b4_cpp_guard],
+[[YY_]b4_tocpp(m4_defn([b4_prefix])/[$1])[_INCLUDED]])
+
+
+# b4_cpp_guard_open(FILE)
+# b4_cpp_guard_close(FILE)
+# ------------------------
+# If FILE does not expand to nothing, open/close CPP inclusion guards for FILE.
+m4_define([b4_cpp_guard_open],
+[m4_ifval(m4_quote($1),
+[#ifndef b4_cpp_guard([$1])
+# define b4_cpp_guard([$1])])])
+
+m4_define([b4_cpp_guard_close],
+[m4_ifval(m4_quote($1),
+[#endif b4_comment([!b4_cpp_guard([$1])])])])
+
+
## ---------------- ##
## Identification. ##
## ---------------- ##
-# b4_comment(TEXT)
-# ----------------
-m4_define([b4_comment], [/* m4_bpatsubst([$1], [
-], [
- ]) */])
-
# b4_identification
# -----------------
# Depends on individual skeletons to define b4_pure_flag, b4_push_flag, or
# b4_pull_flag if they use the values of the %define variables api.pure or
-# api.push_pull.
+# api.push-pull.
m4_define([b4_identification],
[[/* Identify Bison output. */
#define YYBISON 1
/* Pull parsers. */
#define YYPULL ]b4_pull_flag])[
-
-/* Using locations. */
-#define YYLSP_NEEDED ]b4_locations_flag[
]])
## Default values. ##
## ---------------- ##
+# b4_api_prefix, b4_api_PREFIX
+# ----------------------------
+# Corresponds to %define api.prefix
+b4_percent_define_default([[api.prefix]], [[yy]])
+m4_define([b4_api_prefix],
+[b4_percent_define_get([[api.prefix]])])
+m4_define([b4_api_PREFIX],
+[m4_toupper(b4_api_prefix)])
+
+
+# b4_prefix
+# ---------
+# If the %name-prefix is not given, it is api.prefix.
+m4_define_default([b4_prefix], [b4_api_prefix])
+
# If the %union is not named, its name is YYSTYPE.
-m4_define_default([b4_union_name], [YYSTYPE])
+m4_define_default([b4_union_name], [b4_api_PREFIX[]STYPE])
-# If the %name-prefix is not given, it is yy.
-m4_define_default([b4_prefix], [yy])
## ------------------------ ##
## Pure/impure interfaces. ##
## ------------------------ ##
+# b4_lex_formals
+# --------------
+# All the yylex formal arguments.
+# b4_lex_param arrives quoted twice, but we want to keep only one level.
+m4_define([b4_lex_formals],
+[b4_pure_if([[[[YYSTYPE *yylvalp]], [[&yylval]]][]dnl
+b4_locations_if([, [[YYLTYPE *yyllocp], [&yylloc]]])])dnl
+m4_ifdef([b4_lex_param], [, ]b4_lex_param)])
+
+
+# b4_lex
+# ------
+# Call yylex.
+m4_define([b4_lex],
+[b4_function_call([yylex], [int], b4_lex_formals)])
+
+
# b4_user_args
# ------------
m4_define([b4_user_args],
-[m4_ifset([b4_parse_param], [, b4_c_args(b4_parse_param)])])
+[m4_ifset([b4_parse_param], [, b4_args(b4_parse_param)])])
# b4_parse_param
# the formal name to FORMAL, and evaluating the BODY.
m4_define([b4_parse_param_for],
[m4_foreach([$1_$2], m4_defn([b4_parse_param]),
-[m4_pushdef([$1], m4_fst($1_$2))dnl
+[m4_pushdef([$1], m4_unquote(m4_car($1_$2)))dnl
m4_pushdef([$2], m4_shift($1_$2))dnl
$3[]dnl
m4_popdef([$2])dnl
m4_popdef([$1])dnl
])])
-# b4_parse_param_use
-# ------------------
-# `YYUSE' all the parse-params.
+# b4_parse_param_use([VAL], [LOC])
+# --------------------------------
+# 'YYUSE' VAL, LOC if locations are enabled, and all the parse-params.
m4_define([b4_parse_param_use],
-[b4_parse_param_for([Decl], [Formal], [ YYUSE (Formal);
+[m4_ifvaln([$1], [ YYUSE ([$1]);])dnl
+b4_locations_if([m4_ifvaln([$2], [ YYUSE ([$2]);])])dnl
+b4_parse_param_for([Decl], [Formal], [ YYUSE (Formal);
])dnl
])
m4_eval([0 <= $1]), [1], [unsigned int],
- [int])])
+ [int])])
# b4_int_type_for(NAME)
# ---------------------
# Return the smallest int type able to handle numbers ranging from
-# `NAME_min' to `NAME_max' (included).
+# 'NAME_min' to 'NAME_max' (included).
m4_define([b4_int_type_for],
[b4_int_type($1_min, $1_max)])
+
+# b4_table_value_equals(TABLE, VALUE, LITERAL)
+# --------------------------------------------
+# Without inducing a comparison warning from the compiler, check if the
+# literal value LITERAL equals VALUE from table TABLE, which must have
+# TABLE_min and TABLE_max defined.
+m4_define([b4_table_value_equals],
+[m4_if(m4_eval($3 < m4_indir([b4_]$1[_min])
+ || m4_indir([b4_]$1[_max]) < $3), [1],
+ [[0]],
+ [(!!(($2) == ($3)))])])
+
+
+## ----------------- ##
+## Compiler issues. ##
+## ----------------- ##
+
+# b4_attribute_define
+# -------------------
+# Provide portability for __attribute__.
+m4_define([b4_attribute_define],
+[#ifndef __attribute__
+/* This feature is available in gcc versions 2.5 and later. */
+# if (! defined __GNUC__ || __GNUC__ < 2 \
+ || (__GNUC__ == 2 && __GNUC_MINOR__ < 5))
+# define __attribute__(Spec) /* empty */
+# endif
+#endif
+
+/* Suppress unused-variable warnings by "using" E. */
+#if ! defined lint || defined __GNUC__
+# define YYUSE(E) ((void) (E))
+#else
+# define YYUSE(E) /* empty */
+#endif
+
+#if defined __GNUC__ && 407 <= __GNUC__ * 100 + __GNUC_MINOR__
+/* Suppress an incorrect diagnostic about yylval being uninitialized. */
+# define YY_IGNORE_MAYBE_UNINITIALIZED_BEGIN \
+ _Pragma ("GCC diagnostic push") \
+ _Pragma ("GCC diagnostic ignored \"-Wuninitialized\"")\
+ _Pragma ("GCC diagnostic ignored \"-Wmaybe-uninitialized\"")
+# define YY_IGNORE_MAYBE_UNINITIALIZED_END \
+ _Pragma ("GCC diagnostic pop")
+#else
+# define YY_INITIAL_VALUE(Value) Value
+#endif
+#ifndef YY_IGNORE_MAYBE_UNINITIALIZED_BEGIN
+# define YY_IGNORE_MAYBE_UNINITIALIZED_BEGIN
+# define YY_IGNORE_MAYBE_UNINITIALIZED_END
+#endif
+#ifndef YY_INITIAL_VALUE
+# define YY_INITIAL_VALUE(Value) /* Nothing. */
+#endif
+])
+
+
## ---------##
## Values. ##
## ---------##
+
+# b4_null_define
+# --------------
+# Portability issues: define a YY_NULL appropriate for the current
+# language (C, C++98, or C++11).
+m4_define([b4_null_define],
+[# ifndef YY_NULL
+# if defined __cplusplus && 201103L <= __cplusplus
+# define YY_NULL nullptr
+# else
+# define YY_NULL 0
+# endif
+# endif[]dnl
+])
+
+
# b4_null
----------
-# Return a null pointer constant. NULL infringes on the user name
-# space in C, so use 0 rather than NULL.
-m4_define([b4_null], [0])
+# -------
+# Return a null pointer constant.
+m4_define([b4_null], [YY_NULL])
+
+# b4_integral_parser_table_define(TABLE-NAME, CONTENT, COMMENT)
+# -------------------------------------------------------------
+# Define "yy<TABLE-NAME>" whose contents is CONTENT.
+m4_define([b4_integral_parser_table_define],
+[m4_ifvaln([$3], [b4_comment([$3], [ ])])dnl
+static const b4_int_type_for([$2]) yy$1[[]] =
+{
+ $2
+};dnl
+])
## ------------------------- ##
## Assigning token numbers. ##
## ------------------------- ##
-# b4_token_define(TOKEN-NAME, TOKEN-NUMBER)
-# -----------------------------------------
+# b4_token_define(TOKEN-NUM)
+# --------------------------
# Output the definition of this token as #define.
m4_define([b4_token_define],
-[#define $1 $2
-])
+[b4_token_format([#define %s %s], [$1])])
-
-# b4_token_defines(LIST-OF-PAIRS-TOKEN-NAME-TOKEN-NUMBER)
-# -------------------------------------------------------
-# Output the definition of the tokens (if there are) as #defines.
+# b4_token_defines
+# ----------------
+# Output the definition of the tokens.
m4_define([b4_token_defines],
-[m4_if([$@], [[]], [],
-[/* Tokens. */
-m4_map([b4_token_define], [$@])])
-])
+[b4_any_token_visible_if([/* Tokens. */
+m4_join([
+], b4_symbol_map([b4_token_define]))
+])])
-# b4_token_enum(TOKEN-NAME, TOKEN-NUMBER)
-# ---------------------------------------
+# b4_token_enum(TOKEN-NUM)
+# ------------------------
# Output the definition of this token as an enum.
m4_define([b4_token_enum],
-[$1 = $2])
+[b4_token_format([%s = %s], [$1])])
-# b4_token_enums(LIST-OF-PAIRS-TOKEN-NAME-TOKEN-NUMBER)
-# -----------------------------------------------------
+# b4_token_enums
+# --------------
# Output the definition of the tokens (if there are) as enums.
m4_define([b4_token_enums],
-[m4_if([$@], [[]], [],
-[/* Tokens. */
-#ifndef YYTOKENTYPE
-# define YYTOKENTYPE
- /* Put the tokens into the symbol table, so that GDB and other debuggers
- know about them. */
- enum yytokentype {
-m4_map_sep([ b4_token_enum], [,
-],
- [$@])
- };
+[b4_any_token_visible_if([[/* Token type. */
+#ifndef ]b4_api_PREFIX[TOKENTYPE
+# define ]b4_api_PREFIX[TOKENTYPE
+ enum ]b4_api_prefix[tokentype
+ {
+ ]m4_join([,
+ ],
+ b4_symbol_map([b4_token_enum]))[
+ };
#endif
-])])
+]])])
-# b4_token_enums_defines(LIST-OF-PAIRS-TOKEN-NAME-TOKEN-NUMBER)
-# -------------------------------------------------------------
-# Output the definition of the tokens (if there are any) as enums and, if POSIX
-# Yacc is enabled, as #defines.
+# b4_token_enums_defines
+# ----------------------
+# Output the definition of the tokens (if there are any) as enums and,
+# if POSIX Yacc is enabled, as #defines.
m4_define([b4_token_enums_defines],
-[b4_token_enums($@)b4_yacc_if([b4_token_defines($@)], [])
-])
+[b4_token_enums[]b4_yacc_if([b4_token_defines])])
+## ----------------- ##
+## Semantic Values. ##
+## ----------------- ##
-## --------------------------------------------- ##
-## Defining C functions in both K&R and ANSI-C. ##
-## --------------------------------------------- ##
+# b4_symbol_value(VAL, [TYPE])
+# ----------------------------
+# Given a semantic value VAL ($$, $1 etc.), extract its value of type
+# TYPE if TYPE is given, otherwise just return VAL. The result can be
+# used safetly, it is put in parens to avoid nasty precedence issues.
+# TYPE is *not* put in braces, provide some if needed.
+m4_define([b4_symbol_value],
+[($1[]m4_ifval([$2], [.$2]))])
-# b4_modern_c
-# -----------
-# A predicate useful in #if to determine whether C is ancient or modern.
-#
-# If __STDC__ is defined, the compiler is modern. IBM xlc 7.0 when run
-# as 'cc' doesn't define __STDC__ (or __STDC_VERSION__) for pedantic
-# reasons, but it defines __C99__FUNC__ so check that as well.
-# Microsoft C normally doesn't define these macros, but it defines _MSC_VER.
-# Consider a C++ compiler to be modern if it defines __cplusplus.
-#
-m4_define([b4_c_modern],
- [[(defined __STDC__ || defined __C99__FUNC__ \
- || defined __cplusplus || defined _MSC_VER)]])
-# b4_c_function_def(NAME, RETURN-VALUE, [DECL1, NAME1], ...)
-# ----------------------------------------------------------
-# Declare the function NAME.
-m4_define([b4_c_function_def],
-[#if b4_c_modern
-b4_c_ansi_function_def($@)
-#else
-$2
-$1 (b4_c_knr_formal_names(m4_shiftn(2, $@)))
-b4_c_knr_formal_decls(m4_shiftn(2, $@))
-#endif[]dnl
-])
+## ---------------------- ##
+## Defining C functions. ##
+## ---------------------- ##
-# b4_c_ansi_function_def(NAME, RETURN-VALUE, [DECL1, NAME1], ...)
-# ---------------------------------------------------------------
-# Declare the function NAME in ANSI.
-m4_define([b4_c_ansi_function_def],
+
+# b4_function_define(NAME, RETURN-VALUE, [DECL1, NAME1], ...)
+# -----------------------------------------------------------
+# Declare the function NAME in C.
+m4_define([b4_function_define],
[$2
-$1 (b4_c_ansi_formals(m4_shiftn(2, $@)))[]dnl
+$1 (b4_formals(m4_shift2($@)))[]dnl
])
-# b4_c_ansi_formals([DECL1, NAME1], ...)
-# --------------------------------------
-# Output the arguments ANSI-C definition.
-m4_define([b4_c_ansi_formals],
-[m4_case([$@],
- [], [void],
- [[]], [void],
- [m4_map_sep([b4_c_ansi_formal], [, ], [$@])])])
+# b4_formals([DECL1, NAME1], ...)
+# -------------------------------
+# The formal arguments of a C function definition.
+m4_define([b4_formals],
+[m4_if([$#], [0], [void],
+ [$#$1], [1], [void],
+ [m4_map_sep([b4_formal], [, ], [$@])])])
-m4_define([b4_c_ansi_formal],
+m4_define([b4_formal],
[$1])
-# b4_c_knr_formal_names([DECL1, NAME1], ...)
-# ------------------------------------------
-# Output the argument names.
-m4_define([b4_c_knr_formal_names],
-[m4_map_sep([b4_c_knr_formal_name], [, ], [$@])])
-
-m4_define([b4_c_knr_formal_name],
-[$2])
-
-
-# b4_c_knr_formal_decls([DECL1, NAME1], ...)
-# ------------------------------------------
-# Output the K&R argument declarations.
-m4_define([b4_c_knr_formal_decls],
-[m4_map_sep([b4_c_knr_formal_decl],
- [
-],
- [$@])])
-
-m4_define([b4_c_knr_formal_decl],
-[ $1;])
+## ----------------------- ##
+## Declaring C functions. ##
+## ----------------------- ##
-## ------------------------------------------------------------ ##
-## Declaring (prototyping) C functions in both K&R and ANSI-C. ##
-## ------------------------------------------------------------ ##
-
-
-# b4_c_function_decl(NAME, RETURN-VALUE, [DECL1, NAME1], ...)
-# -----------------------------------------------------------
-# Declare the function NAME.
-m4_define([b4_c_function_decl],
-[#if defined __STDC__ || defined __cplusplus
-b4_c_ansi_function_decl($@)
-#else
-$2 $1 ();
-#endif[]dnl
-])
-
-
-# b4_c_ansi_function_decl(NAME, RETURN-VALUE, [DECL1, NAME1], ...)
-# ----------------------------------------------------------------
+# b4_function_declare(NAME, RETURN-VALUE, [DECL1, NAME1], ...)
+# ------------------------------------------------------------
# Declare the function NAME.
-m4_define([b4_c_ansi_function_decl],
-[$2 $1 (b4_c_ansi_formals(m4_shiftn(2, $@)));[]dnl
+m4_define([b4_function_declare],
+[$2 $1 (b4_formals(m4_shift2($@)));[]dnl
])
## --------------------- ##
-# b4_c_function_call(NAME, RETURN-VALUE, [DECL1, NAME1], ...)
+# b4_function_call(NAME, RETURN-VALUE, [DECL1, NAME1], ...)
# -----------------------------------------------------------
# Call the function NAME with arguments NAME1, NAME2 etc.
-m4_define([b4_c_function_call],
-[$1 (b4_c_args(m4_shiftn(2, $@)))[]dnl
+m4_define([b4_function_call],
+[$1 (b4_args(m4_shift2($@)))[]dnl
])
-# b4_c_args([DECL1, NAME1], ...)
-# ------------------------------
+# b4_args([DECL1, NAME1], ...)
+# ----------------------------
# Output the arguments NAME1, NAME2...
-m4_define([b4_c_args],
-[m4_map_sep([b4_c_arg], [, ], [$@])])
+m4_define([b4_args],
+[m4_map_sep([b4_arg], [, ], [$@])])
-m4_define([b4_c_arg],
+m4_define([b4_arg],
[$2])
## ----------- ##
# b4_sync_start(LINE, FILE)
-# -----------------------
+# -------------------------
m4_define([b4_sync_start], [[#]line $1 $2])
m4_define([b4_case],
[ case $1:
$2
+b4_syncline([@oline@], [@ofile@])
break;])
-# b4_symbol_actions(FILENAME, LINENO,
-# SYMBOL-TAG, SYMBOL-NUM,
-# SYMBOL-ACTION, SYMBOL-TYPENAME)
-# -------------------------------------------------
-m4_define([b4_symbol_actions],
-[m4_pushdef([b4_dollar_dollar],
- [m4_ifval([$6], [(yyvaluep->$6)], [(*yyvaluep)])])dnl
-m4_pushdef([b4_at_dollar], [(*yylocationp)])dnl
- case $4: /* $3 */
-b4_syncline([$2], [$1])
- $5;
+
+# b4_predicate_case(LABEL, CONDITIONS)
+# ------------------------------------
+m4_define([b4_predicate_case],
+[ case $1:
+ if (! ($2)) YYERROR;
b4_syncline([@oline@], [@ofile@])
- break;
-m4_popdef([b4_at_dollar])dnl
-m4_popdef([b4_dollar_dollar])dnl
-])
+ break;])
-# b4_yydestruct_generate(FUNCTION-DECLARATOR)
-# -------------------------------------------
-# Generate the "yydestruct" function, which declaration is issued using
-# FUNCTION-DECLARATOR, which may be "b4_c_ansi_function_def" for ISO C
-# or "b4_c_function_def" for K&R.
-m4_define_default([b4_yydestruct_generate],
+# b4_yydestruct_define
+# --------------------
+# Define the "yydestruct" function.
+m4_define_default([b4_yydestruct_define],
[[/*-----------------------------------------------.
| Release the memory associated to this symbol. |
`-----------------------------------------------*/
-/*ARGSUSED*/
-]$1([yydestruct],
+]b4_function_define([yydestruct],
[static void],
[[const char *yymsg], [yymsg]],
[[int yytype], [yytype]],
b4_locations_if( [, [[YYLTYPE *yylocationp], [yylocationp]]])[]dnl
m4_ifset([b4_parse_param], [, b4_parse_param]))[
{
- YYUSE (yyvaluep);
-]b4_locations_if([ YYUSE (yylocationp);
-])dnl
-b4_parse_param_use[]dnl
-[
- if (!yymsg)
+]b4_parse_param_use([yyvaluep], [yylocationp])dnl
+[ if (!yymsg)
yymsg = "Deleting";
YY_SYMBOL_PRINT (yymsg, yytype, yyvaluep, yylocationp);
- switch (yytype)
- {
-]m4_map([b4_symbol_actions], m4_defn([b4_symbol_destructors]))[
- default:
- break;
- }
+ YY_IGNORE_MAYBE_UNINITIALIZED_BEGIN
+ ]b4_symbol_actions([destructor])[
+ YY_IGNORE_MAYBE_UNINITIALIZED_END
}]dnl
])
-# b4_yy_symbol_print_generate(FUNCTION-DECLARATOR)
-# ------------------------------------------------
-# Generate the "yy_symbol_print" function, which declaration is issued using
-# FUNCTION-DECLARATOR, which may be "b4_c_ansi_function_def" for ISO C
-# or "b4_c_function_def" for K&R.
-m4_define_default([b4_yy_symbol_print_generate],
+# b4_yy_symbol_print_define
+# -------------------------
+# Define the "yy_symbol_print" function.
+m4_define_default([b4_yy_symbol_print_define],
[[
-/*--------------------------------.
-| Print this symbol on YYOUTPUT. |
-`--------------------------------*/
+/*----------------------------------------.
+| Print this symbol's value on YYOUTPUT. |
+`----------------------------------------*/
-/*ARGSUSED*/
-]$1([yy_symbol_value_print],
+]b4_function_define([yy_symbol_value_print],
[static void],
- [[FILE *yyoutput], [yyoutput]],
- [[int yytype], [yytype]],
- [[YYSTYPE const * const yyvaluep], [yyvaluep]][]dnl
+ [[FILE *yyoutput], [yyoutput]],
+ [[int yytype], [yytype]],
+ [[YYSTYPE const * const yyvaluep], [yyvaluep]][]dnl
b4_locations_if([, [[YYLTYPE const * const yylocationp], [yylocationp]]])[]dnl
m4_ifset([b4_parse_param], [, b4_parse_param]))[
{
- if (!yyvaluep)
- return;
-]b4_locations_if([ YYUSE (yylocationp);
-])dnl
-b4_parse_param_use[]dnl
-[# ifdef YYPRINT
+ FILE *yyo = yyoutput;
+]b4_parse_param_use([yyo], [yylocationp])dnl
+[ if (!yyvaluep)
+ return;]
+dnl glr.c does not feature yytoknum.
+m4_if(b4_skeleton, ["yacc.c"],
+[[# ifdef YYPRINT
if (yytype < YYNTOKENS)
YYPRINT (yyoutput, yytoknum[yytype], *yyvaluep);
-# else
- YYUSE (yyoutput);
# endif
- switch (yytype)
- {
-]m4_map([b4_symbol_actions], m4_defn([b4_symbol_printers]))dnl
-[ default:
- break;
- }
+]])dnl
+ b4_symbol_actions([printer])[
}
| Print this symbol on YYOUTPUT. |
`--------------------------------*/
-]$1([yy_symbol_print],
+]b4_function_define([yy_symbol_print],
[static void],
- [[FILE *yyoutput], [yyoutput]],
- [[int yytype], [yytype]],
- [[YYSTYPE const * const yyvaluep], [yyvaluep]][]dnl
+ [[FILE *yyoutput], [yyoutput]],
+ [[int yytype], [yytype]],
+ [[YYSTYPE const * const yyvaluep], [yyvaluep]][]dnl
b4_locations_if([, [[YYLTYPE const * const yylocationp], [yylocationp]]])[]dnl
m4_ifset([b4_parse_param], [, b4_parse_param]))[
{
- if (yytype < YYNTOKENS)
- YYFPRINTF (yyoutput, "token %s (", yytname[yytype]);
- else
- YYFPRINTF (yyoutput, "nterm %s (", yytname[yytype]);
+ YYFPRINTF (yyoutput, "%s %s (",
+ yytype < YYNTOKENS ? "token" : "nterm", yytname[yytype]);
]b4_locations_if([ YY_LOCATION_PRINT (yyoutput, *yylocationp);
YYFPRINTF (yyoutput, ": ");
YYFPRINTF (yyoutput, ")");
}]dnl
])
+
+
+## ---------------- ##
+## api.value.type. ##
+## ---------------- ##
+
+
+# ---------------------- #
+# api.value.type=union. #
+# ---------------------- #
+
+# b4_symbol_type_register(SYMBOL-NUM)
+# -----------------------------------
+# Symbol SYMBOL-NUM has a type (for variant) instead of a type-tag.
+# Extend the definition of %union's body with a field of that type,
+# and extend the symbol's "type" field to point to the field name,
+# instead of the type name.
+m4_define([b4_symbol_type_register],
+[m4_define([b4_symbol($1, type_tag)],
+ [b4_symbol_if([$1], [has_id],
+ [b4_symbol([$1], [id])],
+ [yytype_[]b4_symbol([$1], [number])])])dnl
+m4_append([b4_user_union_members],
+m4_expand([
+ b4_symbol_tag_comment([$1])dnl
+ b4_symbol([$1], [type]) b4_symbol([$1], [type_tag]);]))
+])
+
+
+# b4_type_define_tag(SYMBOL1-NUM, ...)
+# ------------------------------------
+# For the batch of symbols SYMBOL1-NUM... (which all have the same
+# type), enhance the %union definition for each of them, and set
+# there "type" field to the field tag name, instead of the type name.
+m4_define([b4_type_define_tag],
+[b4_symbol_if([$1], [has_type],
+ [m4_map([b4_symbol_type_register], [$@])])
+])
+
+
+# b4_symbol_value_union(VAL, [TYPE])
+# ----------------------------------
+# Same of b4_symbol_value, but when api.value.type=union.
+m4_define([b4_symbol_value_union],
+[m4_ifval([$2],
+ [(*($2*)(&$1))],
+ [$1])])
+])
+
+
+# b4_value_type_setup_union
+# -------------------------
+# Setup support for api.value.type=union. Symbols are defined with a
+# type instead of a union member name: build the corresponding union,
+# and give the symbols their tag.
+m4_define([b4_value_type_setup_union],
+[m4_define([b4_union_members])
+b4_type_foreach([b4_type_define_tag])
+m4_copy_force([b4_symbol_value_union], [b4_symbol_value])
+])
+
+
+# ---------------- #
+# api.value.type. #
+# ---------------- #
+
+
+# b4_value_type_setup_variant
+# ---------------------------
+# Setup support for api.value.type=variant. By default, fail, specialized
+# by other skeletons.
+m4_define([b4_value_type_setup_variant],
+[b4_complain_at(b4_percent_define_get_loc([[api.value.type]]),
+ [['%s' does not support '%s']],
+ [b4_skeleton],
+ [%define api.value.type variant])])
+
+
+# _b4_value_type_setup_keyword
+# ----------------------------
+# api.value.type is defined with a keyword/string syntax. Check if
+# that is properly defined, and prepare its use.
+m4_define([_b4_value_type_setup_keyword],
+[b4_percent_define_check_values([[[[api.value.type]],
+ [[none]],
+ [[union]],
+ [[union-directive]],
+ [[variant]],
+ [[yystype]]]])dnl
+m4_case(b4_percent_define_get([[api.value.type]]),
+ [union], [b4_value_type_setup_union],
+ [variant], [b4_value_type_setup_variant])])
+
+
+# b4_value_type_setup
+# -------------------
+# Check if api.value.type is properly defined, and possibly prepare
+# its use.
+b4_define_silent([b4_value_type_setup],
+[# Define default value.
+b4_percent_define_ifdef([[api.value.type]], [],
+[# %union => api.value.type=union-directive
+m4_ifdef([b4_union_members],
+[m4_define([b4_percent_define_kind(api.value.type)], [keyword])
+m4_define([b4_percent_define(api.value.type)], [union-directive])],
+[# no tag seen => api.value.type={int}
+m4_if(b4_tag_seen_flag, 0,
+[m4_define([b4_percent_define_kind(api.value.type)], [code])
+m4_define([b4_percent_define(api.value.type)], [int])],
+[# otherwise api.value.type=yystype
+m4_define([b4_percent_define_kind(api.value.type)], [keyword])
+m4_define([b4_percent_define(api.value.type)], [yystype])])])])
+
+# Set up.
+m4_bmatch(b4_percent_define_get_kind([[api.value.type]]),
+ [keyword\|string], [_b4_value_type_setup_keyword])
+])
+
+
+## -------------- ##
+## Declarations. ##
+## -------------- ##
+
+
+# b4_value_type_define
+# --------------------
+m4_define([b4_value_type_define],
+[b4_value_type_setup[]dnl
+/* Value type. */
+m4_bmatch(b4_percent_define_get_kind([[api.value.type]]),
+[code],
+[[#if ! defined ]b4_api_PREFIX[STYPE && ! defined ]b4_api_PREFIX[STYPE_IS_DECLARED
+typedef ]b4_percent_define_get([[api.value.type]])[ ]b4_api_PREFIX[STYPE;
+# define ]b4_api_PREFIX[STYPE_IS_TRIVIAL 1
+# define ]b4_api_PREFIX[STYPE_IS_DECLARED 1
+#endif
+]],
+[m4_bmatch(b4_percent_define_get([[api.value.type]]),
+[union\|union-directive],
+[[#if ! defined ]b4_api_PREFIX[STYPE && ! defined ]b4_api_PREFIX[STYPE_IS_DECLARED
+typedef union ]b4_union_name[ ]b4_api_PREFIX[STYPE;
+union ]b4_union_name[
+{
+]b4_user_union_members[
+};
+# define ]b4_api_PREFIX[STYPE_IS_TRIVIAL 1
+# define ]b4_api_PREFIX[STYPE_IS_DECLARED 1
+#endif
+]])])])
+
+
+# b4_location_type_define
+# -----------------------
+m4_define([b4_location_type_define],
+[[/* Location type. */
+#if ! defined ]b4_api_PREFIX[LTYPE && ! defined ]b4_api_PREFIX[LTYPE_IS_DECLARED
+typedef struct ]b4_api_PREFIX[LTYPE ]b4_api_PREFIX[LTYPE;
+struct ]b4_api_PREFIX[LTYPE
+{
+ int first_line;
+ int first_column;
+ int last_line;
+ int last_column;
+};
+# define ]b4_api_PREFIX[LTYPE_IS_DECLARED 1
+# define ]b4_api_PREFIX[LTYPE_IS_TRIVIAL 1
+#endif
+]])
+
+
+# b4_declare_yylstype
+# -------------------
+# Declarations that might either go into the header (if --defines) or
+# in the parser body. Declare YYSTYPE/YYLTYPE, and yylval/yylloc.
+m4_define([b4_declare_yylstype],
+[b4_value_type_define[]b4_locations_if([
+b4_location_type_define])
+
+b4_pure_if([], [[extern ]b4_api_PREFIX[STYPE ]b4_prefix[lval;
+]b4_locations_if([[extern ]b4_api_PREFIX[LTYPE ]b4_prefix[lloc;]])])[]dnl
+])
+
+
+# b4_YYDEBUG_define
+# -----------------
+m4_define([b4_YYDEBUG_define],
+[[/* Debug traces. */
+]m4_if(b4_api_prefix, [yy],
+[[#ifndef YYDEBUG
+# define YYDEBUG ]b4_parse_trace_if([1], [0])[
+#endif]],
+[[#ifndef ]b4_api_PREFIX[DEBUG
+# if defined YYDEBUG
+#if YYDEBUG
+# define ]b4_api_PREFIX[DEBUG 1
+# else
+# define ]b4_api_PREFIX[DEBUG 0
+# endif
+# else /* ! defined YYDEBUG */
+# define ]b4_api_PREFIX[DEBUG ]b4_parse_trace_if([1], [0])[
+# endif /* ! defined YYDEBUG */
+#endif /* ! defined ]b4_api_PREFIX[DEBUG */]])[]dnl
+])
+
+# b4_declare_yydebug
+# ------------------
+m4_define([b4_declare_yydebug],
+[b4_YYDEBUG_define[
+#if ]b4_api_PREFIX[DEBUG
+extern int ]b4_prefix[debug;
+#endif][]dnl
+])
+
+# b4_yylloc_default_define
+# ------------------------
+# Define YYLLOC_DEFAULT.
+m4_define([b4_yylloc_default_define],
+[[/* YYLLOC_DEFAULT -- Set CURRENT to span from RHS[1] to RHS[N].
+ If N is 0, then set CURRENT to the empty location which ends
+ the previous symbol: RHS[0] (always defined). */
+
+#ifndef YYLLOC_DEFAULT
+# define YYLLOC_DEFAULT(Current, Rhs, N) \
+ do \
+ if (N) \
+ { \
+ (Current).first_line = YYRHSLOC (Rhs, 1).first_line; \
+ (Current).first_column = YYRHSLOC (Rhs, 1).first_column; \
+ (Current).last_line = YYRHSLOC (Rhs, N).last_line; \
+ (Current).last_column = YYRHSLOC (Rhs, N).last_column; \
+ } \
+ else \
+ { \
+ (Current).first_line = (Current).last_line = \
+ YYRHSLOC (Rhs, 0).last_line; \
+ (Current).first_column = (Current).last_column = \
+ YYRHSLOC (Rhs, 0).last_column; \
+ } \
+ while (0)
+#endif
+]])
+
+# b4_yy_location_print_define
+# ---------------------------
+# Define YY_LOCATION_PRINT.
+m4_define([b4_yy_location_print_define],
+[b4_locations_if([[
+/* YY_LOCATION_PRINT -- Print the location on the stream.
+ This macro was not mandated originally: define only if we know
+ we won't break user code: when these are the locations we know. */
+
+#ifndef YY_LOCATION_PRINT
+# if defined ]b4_api_PREFIX[LTYPE_IS_TRIVIAL && ]b4_api_PREFIX[LTYPE_IS_TRIVIAL
+
+/* Print *YYLOCP on YYO. Private, do not rely on its existence. */
+
+__attribute__((__unused__))
+]b4_function_define([yy_location_print_],
+ [static unsigned],
+ [[FILE *yyo], [yyo]],
+ [[YYLTYPE const * const yylocp], [yylocp]])[
+{
+ unsigned res = 0;
+ int end_col = 0 != yylocp->last_column ? yylocp->last_column - 1 : 0;
+ if (0 <= yylocp->first_line)
+ {
+ res += YYFPRINTF (yyo, "%d", yylocp->first_line);
+ if (0 <= yylocp->first_column)
+ res += YYFPRINTF (yyo, ".%d", yylocp->first_column);
+ }
+ if (0 <= yylocp->last_line)
+ {
+ if (yylocp->first_line < yylocp->last_line)
+ {
+ res += YYFPRINTF (yyo, "-%d", yylocp->last_line);
+ if (0 <= end_col)
+ res += YYFPRINTF (yyo, ".%d", end_col);
+ }
+ else if (0 <= end_col && yylocp->first_column < end_col)
+ res += YYFPRINTF (yyo, "-%d", end_col);
+ }
+ return res;
+ }
+
+# define YY_LOCATION_PRINT(File, Loc) \
+ yy_location_print_ (File, &(Loc))
+
+# else
+# define YY_LOCATION_PRINT(File, Loc) ((void) 0)
+# endif
+#endif]],
+[[/* This macro is provided for backward compatibility. */
+#ifndef YY_LOCATION_PRINT
+# define YY_LOCATION_PRINT(File, Loc) ((void) 0)
+#endif]])
+])
+
+# b4_yyloc_default
+# ----------------
+# Expand to a possible default value for yylloc.
+m4_define([b4_yyloc_default],
+[[
+# if defined ]b4_api_PREFIX[LTYPE_IS_TRIVIAL && ]b4_api_PREFIX[LTYPE_IS_TRIVIAL
+ = { ]m4_join([, ],
+ m4_defn([b4_location_initial_line]),
+ m4_defn([b4_location_initial_column]),
+ m4_defn([b4_location_initial_line]),
+ m4_defn([b4_location_initial_column]))[ }
+# endif
+]])